Programming Forums > Application Development > Assembly

Klarre · Aug 17th, 2006, 6:54 AM

I have a class with a member function that I wish to implement using MASM.

class Foo
{
public:
    Foo() {}
    ~Foo() {}

    int adder(int, int); // <- This should be implemented using MASM
};

(Toggle Plain Text)

;ASM source
.486
.model flat, stdcall
option casemap :none

.code

adder proc arg1:dword, arg2:dword
	mov eax, arg1
	add eax, arg2

	ret

adder endp

end

I know how to implement C function, but now C++. I have read this http://www.codeproject.com/cpp/Using...nesVisualC.asp but with no success. How, and where, do I declare the function? Something like

(Toggle Plain Text)

extern "C" int __stdcall adder(int, int);

or similiar should be somewhere I guess...

(Toggle Plain Text)

int main()
{
    Foo foo = Foo();
    foo.adder(1, 2);
}

This does not work, cause I don't know how to declare the function. Anyone who can help me out with this?

/Thanks for your help!

/Klarre

Wizard1988 · Aug 17th, 2006, 7:24 AM

Try declaring it right after including headers.

Klarre · Aug 17th, 2006, 7:34 AM

Tried this

(Toggle Plain Text)

#include "foo.h"
extern "C" int __stdcall adder(int, int);
#include <iostream>

int main()
{
	Foo foo = Foo();
	std::cout << foo.adder(4, 5) << std::endl;

	system("pause");

	return 0;
}

Visual Studio gave me this compiler error:

(Toggle Plain Text)

error C2039: 'adder' : is not a member of 'Foo'

DaWei · Aug 17th, 2006, 9:02 AM

Where are you doing anything to associate the definition with the class?

Eoin · Aug 17th, 2006, 9:05 AM

This is a bit tough and won't be portable, but its not impossible. First you need to understand what exactly a member function is compiled to, then you emulate that with your ASM function. Important things to know are how the name mangling works or not forgetting that VC passes an implicit this pointer to member functions.

I think your best bet is to write the function in C++, compile into debug code, open that up in a debugger to see what exactly VC expects the function to be called and copy that together with the calling convention in your ASM code.

Also check out the Agner Fog's Manuals.

DaWei · Aug 17th, 2006, 9:20 AM

Quote:

won't be portable

LOL!!

Eoin · Aug 17th, 2006, 10:18 AM

Are you laughing at the fact that Assembly is not portable? If so, very fair point

. I ment though that a solution wouldn't be portable across different C++ compilers, even on identical architectures.

Actually Klarre, forgot to ask you an important question, why do you want to be able to write meber functions in ASM? Its easier to write stdcall or ccall ASM functions, build them into an object file or library, link that into your C++ app and then call those functions from inside member, or indeed any, functions.

DaWei · Aug 17th, 2006, 10:26 AM

Yeah, no offense, it just tickled my funnybone when I read it.

Klarre · Aug 17th, 2006, 10:39 AM

Quote:

Originally Posted by Eoin

Actually Klarre, forgot to ask you an important question, why do you want to be able to write meber functions in ASM? Its easier to write stdcall or ccall ASM functions, build them into an object file or library, link that into your C++ app and then call those functions from inside member, or indeed any, functions.

I am just curious about how it works!

Klarre · Aug 17th, 2006, 12:03 PM

I finally got it linked correctly.

(Toggle Plain Text)

class Foo
{
public:
	Foo();
	~Foo();

	int bar();
};

int main()
{
	Foo foo = Foo();
	int x = foo.bar();

	return 0;
}

(Toggle Plain Text)

.386P

; ----------------------------------------------------------------------------
; Foo::Foo()
; ----------------------------------------------------------------------------
_TEXT SEGMENT
??0Foo@@QAE@XZ PROC NEAR
	mov eax, ecx
	ret 0

??0Foo@@QAE@XZ ENDP
_TEXT ENDS

; ----------------------------------------------------------------------------
; Foo::~Foo()
; ----------------------------------------------------------------------------
_TEXT SEGMENT
??1Foo@@QAE@XZ PROC NEAR
	ret 0

??1Foo@@QAE@XZ ENDP
_TEXT ENDS

; ----------------------------------------------------------------------------
; int Foo::bar()
; ----------------------------------------------------------------------------
_TEXT SEGMENT
?bar@Foo@@QAEHXZ PROC NEAR
	mov eax, 4
	ret 0

?bar@Foo@@QAEHXZ ENDP
_TEXT ENDS

END

So now is the next step to play around with variables and other complex stuff.

Thanks alot for your help! See you soon again!

/Klarre

Aug 17th, 2006, 6:54 AM	#1
Klarre Game engine designer Join Date: May 2005 Location: Sweden Posts: 301 Rep Power: 4	Implement C++ functions using MASM I have a class with a member function that I wish to implement using MASM. (Toggle Plain Text) class Foo { public: Foo() {} ~Foo() {} int adder(int, int); // <- This should be implemented using MASM }; class Foo { public: Foo() {} ~Foo() {} int adder(int, int); // <- This should be implemented using MASM }; (Toggle Plain Text) ;ASM source .486 .model flat, stdcall option casemap :none .code adder proc arg1:dword, arg2:dword mov eax, arg1 add eax, arg2 ret adder endp end ;ASM source .486 .model flat, stdcall option casemap :none .code adder proc arg1:dword, arg2:dword mov eax, arg1 add eax, arg2 ret adder endp end I know how to implement C function, but now C++. I have read this http://www.codeproject.com/cpp/Using...nesVisualC.asp but with no success. How, and where, do I declare the function? Something like (Toggle Plain Text) extern "C" int __stdcall adder(int, int); extern "C" int __stdcall adder(int, int); or similiar should be somewhere I guess... (Toggle Plain Text) int main() { Foo foo = Foo(); foo.adder(1, 2); } int main() { Foo foo = Foo(); foo.adder(1, 2); } This does not work, cause I don't know how to declare the function. Anyone who can help me out with this? /Thanks for your help! /Klarre __________________ http://www.klarre.se

Aug 17th, 2006, 7:24 AM	#2
Wizard1988 Professional Programmer Join Date: Oct 2005 Location: Chitown Posts: 417 Rep Power: 4	Try declaring it right after including headers. __________________ JG-Webdesign

Aug 17th, 2006, 7:34 AM	#3
Klarre Game engine designer Join Date: May 2005 Location: Sweden Posts: 301 Rep Power: 4	Tried this (Toggle Plain Text) #include "foo.h" extern "C" int __stdcall adder(int, int); #include <iostream> int main() { Foo foo = Foo(); std::cout << foo.adder(4, 5) << std::endl; system("pause"); return 0; } #include "foo.h" extern "C" int __stdcall adder(int, int); #include <iostream> int main() { Foo foo = Foo(); std::cout << foo.adder(4, 5) << std::endl; system("pause"); return 0; } Visual Studio gave me this compiler error: (Toggle Plain Text) error C2039: 'adder' : is not a member of 'Foo' error C2039: 'adder' : is not a member of 'Foo' __________________ http://www.klarre.se

Aug 17th, 2006, 9:02 AM	#4
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Where are you doing anything to associate the definition with the class? __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Aug 17th, 2006, 9:05 AM	#5
Eoin Hobbyist Programmer Join Date: Jun 2006 Location: Ireland Posts: 152 Rep Power: 3	This is a bit tough and won't be portable, but its not impossible. First you need to understand what exactly a member function is compiled to, then you emulate that with your ASM function. Important things to know are how the name mangling works or not forgetting that VC passes an implicit this pointer to member functions. I think your best bet is to write the function in C++, compile into debug code, open that up in a debugger to see what exactly VC expects the function to be called and copy that together with the calling convention in your ASM code. Also check out the Agner Fog's Manuals. __________________ Visit my website BinaryNotions.

Aug 17th, 2006, 10:18 AM	#7
Eoin Hobbyist Programmer Join Date: Jun 2006 Location: Ireland Posts: 152 Rep Power: 3	Are you laughing at the fact that Assembly is not portable? If so, very fair point . I ment though that a solution wouldn't be portable across different C++ compilers, even on identical architectures. Actually Klarre, forgot to ask you an important question, why do you want to be able to write meber functions in ASM? Its easier to write stdcall or ccall ASM functions, build them into an object file or library, link that into your C++ app and then call those functions from inside member, or indeed any, functions. __________________ Visit my website BinaryNotions.

Aug 17th, 2006, 10:26 AM	#8
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Yeah, no offense, it just tickled my funnybone when I read it. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Aug 17th, 2006, 12:03 PM	#10
Klarre Game engine designer Join Date: May 2005 Location: Sweden Posts: 301 Rep Power: 4	I finally got it linked correctly. (Toggle Plain Text) class Foo { public: Foo(); ~Foo(); int bar(); }; int main() { Foo foo = Foo(); int x = foo.bar(); return 0; } class Foo { public: Foo(); ~Foo(); int bar(); }; int main() { Foo foo = Foo(); int x = foo.bar(); return 0; } (Toggle Plain Text) .386P ; ---------------------------------------------------------------------------- ; Foo::Foo() ; ---------------------------------------------------------------------------- _TEXT SEGMENT ??0Foo@@QAE@XZ PROC NEAR mov eax, ecx ret 0 ??0Foo@@QAE@XZ ENDP _TEXT ENDS ; ---------------------------------------------------------------------------- ; Foo::~Foo() ; ---------------------------------------------------------------------------- _TEXT SEGMENT ??1Foo@@QAE@XZ PROC NEAR ret 0 ??1Foo@@QAE@XZ ENDP _TEXT ENDS ; ---------------------------------------------------------------------------- ; int Foo::bar() ; ---------------------------------------------------------------------------- _TEXT SEGMENT ?bar@Foo@@QAEHXZ PROC NEAR mov eax, 4 ret 0 ?bar@Foo@@QAEHXZ ENDP _TEXT ENDS END .386P ; ---------------------------------------------------------------------------- ; Foo::Foo() ; ---------------------------------------------------------------------------- _TEXT SEGMENT ??0Foo@@QAE@XZ PROC NEAR mov eax, ecx ret 0 ??0Foo@@QAE@XZ ENDP _TEXT ENDS ; ---------------------------------------------------------------------------- ; Foo::~Foo() ; ---------------------------------------------------------------------------- _TEXT SEGMENT ??1Foo@@QAE@XZ PROC NEAR ret 0 ??1Foo@@QAE@XZ ENDP _TEXT ENDS ; ---------------------------------------------------------------------------- ; int Foo::bar() ; ---------------------------------------------------------------------------- _TEXT SEGMENT ?bar@Foo@@QAEHXZ PROC NEAR mov eax, 4 ret 0 ?bar@Foo@@QAEHXZ ENDP _TEXT ENDS END So now is the next step to play around with variables and other complex stuff. Thanks alot for your help! See you soon again! /Klarre __________________ http://www.klarre.se

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Programming Forums > Application Development > Assembly

Implement C++ functions using MASM